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Report reveals global problem of drug-resistant TB

By Shaoni Bhattacharya

The largest ever survey of drug-resistant tuberculosis has unveiled “worrying” levels of the disease, with health experts warning that the issue is a global problem.

Patients in former Soviet states such as Kazahkstan, Uzbekistan and Estonia are 10 times more likely to have multi-drug resistant TB than in the rest of the world, reveals the World Health Organization report. The new report also reveals disturbing levels in China.

“The crucial thing to bear in mind with TB is this is an airborne infectious disease,” says Paul Sommerfeld, chair of UK charity TB Alert. “It’s not possible to isolate any one part of the world from the rest of the world.”

The WHO is calling for an urgent expansion of TB control measures, including drug resistance surveillance and investment in DOTS, a WHO-inspired treatment strategy.

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“It is in the interest of every country to support rapid scale-up of TB control if we are to overcome multi-drug resistant TB,” says Mario Raviglione, director of WHO’s Stop TB department. “Passport control will not halt drug resistance; investment in global TB prevention will.”

Death sentence

Drug-resistant TB is a serious problem, explained Paul Nunn, WHO report co-ordinator, at its launch on Monday&colon; “Untreated it’s a death sentence. And treatment requires a cocktail of drugs which are very expensive and difficult to administer.”

The treatment for non-resistant TB is much cheaper, but the infection still causes nine million new cases every year, with two million deaths. The WHO calculates that about 300,000 new cases of TB each year are now multi-drug resistant (MDR), sapping already limited resources.

The report, which assessed one-fifth of the world’s new TB cases, the global scope of the problem. It included 77 countries or provinces compared with only 58 in WHO’s 2001 report.

The world’s worst place was Kazahkstan – with 57 per cent of new TB cases being resistant to one drug and 14.2 per cent being MDR. Worryingly, five of the top 10 places in the world for MDR TB had not previously been surveyed. These include Kazahkstan, Uzbekistan, Lithuania, Ecuador and the Liaoning and Henan provinces in China.

Six of the 10 were former Soviet states and the WHO believes the prevalence of MDR TB here is due to the breakdown of public health infrastructure after the collapse of communism.

Selective survival

The new report raises particular concern over China. “If the national prevalence of MDR TB is as high as we found in Liaoning province [about eight per cent], we have major problems in China as well,” warns Nunn. China has an extremely high burden of TB, with about 485,000 new cases every year, he adds.

Selection can happen if patients do not have adequate concentrations of anti-TB drugs or do not complete their course. Once resistant strains gain hold they can also be transmitted through the air in the same way as non-resistant strains.

Of the MDR TB strains currently known, 79 per cent are “super-strains”, says the report. These are resistant to at least three of the four main drugs used to cure TB.